I signed in to my Sonic Charge account on the website and then run the Sonic Charge Authenticator to authorize your installation. Once it shows I can go back to the Sonic Charge App and leave the website, Synplant 2 fails to activate. It will not download or come up in my ableton.

If you ran Sonic Charge Authenticator, then you downloaded and installed it with the multi-installer already. Your plug-in is most likely installed, but the problem is that Ableton did not find and scan it. Ensure that the VST2 Plug-Ins System Folders option is enabled in Settings and then press "rescan".